The Raspberry Pi is coming up on 6 million units sold. An Amiga would sell if the price was right.
The Raspberry Pi can run AROS already and there is no reason that AmigaOS4 or MorphOS couldn't also be ported. If you want PPC then to carve out market share it would need to be cheaper and faster than the Raspberry Pi, which I don't believe is possible (*). However it would need to be able to run Linux etc as well, because most people aren't interested in "Amiga".
(*) The Raspberry Pi 2 was launched early because another competitor was going for faster at a price premium, so I would expect a Raspberry Pi 3 if it looks like someone gets close to competing (which may already happen with the pine64).